as with any backup, don't rely on only backup.app

Apple has updated it since all those articles were written (3/1/2007)

Don't use this software. It does not work. Really.

I used the most recent version and lost a lot of data that could not be recovered.

Some more link regarding backup solutions on a Mac:

Slashdot: Backup Solutions for Mac OS X?
http://ask.slashdot.org/askslashdot/06/12/16/0656212.shtml

The State of Backup and Cloning Tools under Mac OS X
http://blog.plasticsfuture.org/2006/03/05/the-state-of-backup-and-cloning-tools-under-mac-os-x/

Mac Backup Software Harmful
http://blog.plasticsfuture.org/2006/04/23/mac-backup-software-harmful/

MacOS X Backups
http://www.dataexpedition.com/~sbnoble/Tips/backups.html

There have been many narrated tales of Apple Backup going awry. Consider using another solution, anything except this one. Apparently, Apple Backup is very good at backing up data, but unable to properly restore.

Apple's Backup 3 - Hopeless Junk
http://chriswjohnson.blogspot.com/2006/11/apples-backup-3-hopeless-junk.html

Apple’s Backup App is Shit
http://nslog.com/2005/10/17/apples_backup_app_is_shit/

Holy Crap, Apple Backup is Dangerous
http://www.stuffonfire.com/2006/09/04/holy-crap-apple-backup-is-dangerous/

Apple Backup
http://roobasoft.com/blog/2006/03/14/apple-backup/

It's a decent, fairly simple to use backup program that allows scheduling and backing up to multiple types of media. It serves me quite well and as long as it's included in my .Mac subscription I'll continue to use it. Prior to version 3, though, it was pretty bad.